Iron-base alloys



United States Patent 3,232,687 HRGN-BASE ALLOYS Arthur T. Cape, Monterey, Califi, assignor to Coast Metals Inc, Little Ferry, NJ., a corporation of Delaware No Drawing. Filed Jan. 31, 1963, Ser. No. 255,202 1 Claim. (Cl. 75-128) This invention relates generally to iron-base alloys, but has reference more particularly to an alloy of this type which contains substantial amounts of chromium, nickel and cobalt.

A primary object of the invention is to provide an alloy of this type which has good work hardening characteristics, is machinable with carbide cutting tools, and has good high temperature properties, rendering the alloy particularly suitable for use in making dies, forgings, etc.

Another object of the invention is to provide an alloy of the character described having a desired coefiicient of expansion, which is between that of ferrite type material, such as plain carbon steel, and material which is entirely austenitic, such as stainless steel.

A further object of the invention is to provide an alloy of the character described, in which cobalt is present in fairly critical amounts which produce a desirable structure intermediate that of a ferrite material and a wholly austenitic material, andwhich may be termed an unstable austenite.

These desired characteristics are obtained in an alloy which falls within the following ranges of ingredients:

Percent Carbon 1.25-1.75 Chromium 21-23 Molybdenum 12.5

Nickel 3-5 Percent Cobalt 7 9 Silicon, max 1.0 Iron Balance A preferred alloy, within this range, will contain about 1.5% carbon, about 22% chromium, about 2% molybdenum, about 4% nickel, about 8% cobalt, and the balance substantially all iron.

It is important that the chromium be maintained within the aforesaid narrow range, in order that the first crystallization from the liquid is primarily austenite.

For best results, the nickel and cobalt should be maintained in balance, that is to say, the cobalt should be increased as the nickel is increased.

The alloy is particularly adapted as a coating or hardfacing for internal combustion engine valves, as, for example, poppet valves.

Having thus described my invention, I claim:

An iron-base alloy consisting of from about 1.25%

to about 1.75% carbon, from about 21% to about 23% References Cited by the Examiner UNITED STATES PATENTS 5/1937 Oertel -128 8/1950 Payson 75-128 DAVID L. RECK, Primary Examiner.

P. WEINSTEIN, Assistant Examiner. 

